I'm trying to set up an account with OANDA so that I can properly trade the Z12 algo.
I think you're still only getting 50:1 with Oanda? I'd suggest a non-US broker like IG or Global Prime.
You are 100% correct. Unfortunately, neither IG nor Global Prime accept US citizens as clients. If there were a way around it, I'd love to know as I currently can't trade CFD's or get full leverage.